Industrial and commercial electronic equipment, computers being a notable example, typically require multi-conductor cable interconnections between component elements. Because of high frequency operations, there is considerable potential for electro-magnetic interference (EMI) and radio frequency interference (RFI) emissions from the multi-conductor cables. Accordingly, such cables typically are encased within a tubular braided wire shield.
For detachable connection of the cables to the individual components, multi-pin connector assemblies are typically provided. Such connector assemblies typically provide means for grounding of the shield, mechanical strain relief and, of course, joining of the individual cable conductors to the connector pins. Additionally, in a quality installation, the connector assembly will include features for maintaining the integrity of the EMI/RFI shield. An advantageous form of such connector assembly includes the connector proper, containing the connector means and, typically, mechanical arrangements for joining the connector to a mating connector of the opposite sex. In conjunction with the connector proper, there is provided a backshell assembly which is, in effect, a housing attachable to the connector, for containment of the individual cable conductors in the transitional region from the cable proper to the individual cable pin connections.
Conventional backshell assemblies of the general type contemplated by the present invention typically include a tubular split or partially backshell housing, which may be in a straight line or elbow configuration. The front end of the backshell housing is threadedly connectable to the terminating connector. The remote end typically contains a recess for the reception of shield clamping rings which secure the terminal end of the shielding conductor. A cable clamp element is threadedly connectable to the remote end of the backshell housing and serves to force the shield clamping rings into the backshell recess thus tightly clamping the shielding conductor. The cable clamp itself typically contains clamping jaws engageable with the exterior of the multi-conductor cable. The cable clamp and the compressed shield clamping rings together provide for mechanical strain relief.
The above described, multi part connector-backshell assembly is widely used because it provides access to the backs of the connector pins to enable joining of the cable conductors to the terminal connector. The conventional design suffers from a significant disadvantage, however, in that, in a backshell of partially split construction, the length of exposed conductors, beyond the end of the shielding conductor, must be such that, after joining of the conductors to the terminal connector and mechanical securement thereof to the front end of the backshell housing, the free end of the shielding conductor must be accessible for positioning within the shield clamping rings. Once the shield is properly positioned and clamped between the rings, the rings must then be forced axially into the remote end of the backshell housing. This necessitates physical displacement of the multiple conductors within the contained space of the backshell housing. Often, this requires considerable force on the part of the assembly person. In a cable having numerous conductors, the operation is both difficult and time consuming, and not infrequently causes damage to the conductors and/or their connections, particularly the connection of the shielding conductor.
In accordance with the present invention, a novel and improved backshell construction is provided which, while being highly simplified in form, is significantly more effective than previous constructions for the same purpose. The new construction completely eliminates the need to effect forceable mechanical displacement of conductors within the backshell housing during the final assembly. Assembly and disassembly of the connector-backshell structure is simplified and expedited, and damage to the conductors during the closing procedure is greatly reduced.
Importantly, the backshell structure of the present invention provides, in addition to the above mentioned advantages, significantly superior protection against EMI/RFI leakage in the connector-backshell region.
For a better understanding of the above and other features and advantages of the invention, reference should be made to the following detailed description of preferred embodiments of the invention and to the accompanying drawing.